This invention relates to a multifunctional polymeric additive for hydrocarbon compositions, particularly for lubricating oils. The additive is a terpolymer of ethylene/propylene/carboxylic amide.
The instant invention provides polymers which are primarily known for their viscosity modification. Various polymers have been used as viscosity modifiers. Terpolymers of vinyl acetate, an alkyl fumarate and maleic anhydride are taught, for example, in U.S. Pat. No. 3,087,893 and include copolymers made up of from 2 to 15 mole percent of maleic anhydride, 25 to 50 mole percent of an alkyl ester of an alpha, betaunsaturated dicarboxylic acid, and from 40 to 70 mole percent of an alkylene ester of a C.sub.1 to C.sub.6 monocarboxylic acid. Techniques for forming the polymers are also well-known. For example, a terpolyer of an alkyl fumarate, vinyl acetate, and maleic anhydride can be prepared by the process disclosed in the aforementioned U.S. Pat. No. 3,087,893 or by the improved process described in U.S. Pat. No. 3,136,743.
U.S. Pat. No. 3,637,610 teaches a viscosity modifier which is an oil soluble polymer having free carboxylic acid groups which react with amine-containing polymers.